Splice-Variant- and Stage-Specific RNA Editing of the<i>Drosophila</i>GABA Receptor Modulates Agonist Potency

Jones, Andrew K.; Buckingham, Steven D.; Papadaki, M.; Yokota, Maiko; Sattelle, Benedict M.; Matsuda, Kazuhiko; Sattelle, David B.

doi:10.1523/jneurosci.5251-08.2009

Cited by 57 publications

(82 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Met 360 is one of four RNA-editing locations in Rdl. Editing to Val occurs in 10% of adult head Rdl BD transcripts, where Rdl BD is the most common splice isoform of four alternately spliced transcripts (26).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Gene duplication in the major insecticide target site,Rdl, inDrosophila melanogaster

Remnant

Good

Schmidt

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The Resistance to Dieldrin gene, Rdl, encodes a GABA-gated chloride channel subunit that is targeted by cyclodiene and phenylpyrazole insecticides. The gene was first characterized in Drosophila melanogaster by genetic mapping of resistance to the cyclodiene dieldrin. The 4,000-fold resistance observed was due to a single amino acid replacement, Ala 301 to Ser. The equivalent change was subsequently identified in Rdl orthologs of a large range of resistant insect species. Here, we report identification of a duplication at the Rdl locus in D. melanogaster. The 113-kb duplication contains one WT copy of Rdl and a second copy with two point mutations: an Ala 301 to Ser resistance mutation and Met 360 to Ile replacement. Individuals with this duplication exhibit intermediate dieldrin resistance compared with single copy Ser 301 homozygotes, reduced temperature sensitivity, and altered RNA editing associated with the resistant allele. Ectopic recombination between Roo transposable elements is involved in generating this genomic rearrangement. The duplication phenotypes were confirmed by construction of a transgenic, artificial duplication integrating the 55.7-kb Rdl locus with a Ser 301 change into an Ala 301 background. Gene duplications can contribute significantly to the evolution of insecticide resistance, most commonly by increasing the amount of gene product produced. Here however, duplication of the Rdl target site creates permanent heterozygosity, providing unique potential for adaptive mutations to accrue in one copy, without abolishing the endogenous role of an essential gene.T he single point mutation in the Resistance to dieldrin (Rdl) gene represents one of the most significant cases of target site resistance to an insecticide yet observed. Cyclodiene resistance was reported in 62% of insecticide resistant species in the 1980s, following widespread use of cyclodiene insecticides, including dieldrin, which started in the 1950s (1). The nature of the genetic target, Rdl, was discovered after dieldrin was discontinued because of the widespread evolution of resistance in many species. Rdl was first discovered in Drosophila melanogaster using a positional cloning approach. High homology to human GABA receptors confirmed it was the first insect ligand-gated chloride channel subunit identified (2-4). A point mutation in the chloride channel pore-lining domain, replacing alanine 301 with serine, was present in all resistant D. melanogaster strains (5). This mutation provided 4,000-fold resistance when homozygous and lower levels of resistance in heterozygotes (2, 6). The homologous mutation was subsequently found in a large number of cyclodiene-resistant species from many insect orders (7-9), as well as a glycine replacement at the homologous site in some resistant strains of Drosophila simulans and other species (5, 10, 11).Characterization of deficiency lines and inversions in D. melanogaster showed that Rdl is an essential gene (3). Thus, the Ala 301 to Ser or Gly mutation in Rdl exhibits unique properties, p...

show abstract

Section: Resultsmentioning

confidence: 99%

“…Forty-five individual clones were sequenced to identify whether both copies of Rdl were expressed and if the two derived nonsynonomous variants were found in the same copy. This tissue and life stage were chosen to determine whether Met 360 to Val RNA editing still occurred correctly in Ile 360 mutants (26).…”

Section: Resultsmentioning

confidence: 99%

Gene duplication in the major insecticide target site,Rdl, inDrosophila melanogaster

Remnant

Good

Schmidt

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Edited adenosines exhibiting differential developmental regulation may even be found within the same transcript (23,24), yet how this is achieved remains unknown. Previous data has shown that dAdar transcription is low during the larval stages and rapidly peaks at the late pupal and adult stages (25).…”

Section: Stringent Reduction Of Dadar Expression Reveals Differentialmentioning

confidence: 99%

Engineered Alterations in RNA Editing Modulate Complex Behavior in Drosophila

Jepson¹,

Savva²,

Yokose

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

Select proteins involved in electrical and chemical neurotransmission are re-coded at the RNA level via the deamination of particular adenosines to inosine by adenosine deaminases acting on RNA (ADARs). It has been hypothesized that this process, termed RNA editing, acts to "fine-tune" neurophysiological properties in animals and potentially downstream behavioral outputs. However, the extreme phenotypes resulting from deletions of adar loci have precluded investigations into the relationship between ADAR levels, target transcripts, and complex behaviors. Here, we engineer Drosophila hypomorphic for ADAR expression using homologous recombination. A substantial reduction in ADAR activity (>80%) leads to altered circadian motor patterns and abnormal male courtship, although surprisingly, general locomotor coordination is spared. The altered phenotypic landscape in our adar hypomorph is paralleled by an unexpected dichotomous response of ADAR target transcripts, i.e. certain adenosines are minimally affected by dramatic ADAR reduction, whereas editing of others is severely curtailed. Furthermore, we use a novel reporter to map RNA editing activity across the nervous system, and we demonstrate that knockdown of editing in fruitless-expressing neurons is sufficient to modify the male courtship song. Our data demonstrate that network-wide temporal and spatial regulation of ADAR activity can tune the complex system of RNA-editing sites and modulate multiple ethologically relevant behavioral modalities.Informational recoding of RNA by the catalytic deamination of adenosine to inosine proceeds through the action of ADARs 3 (1). Long double strand RNA duplexes exhibiting perfect complementarity can be modified extensively by promiscuous ADAR activity. However, mRNAs may also serve as site-specific substrates for ADARs via base pairing interactions that generate short imperfect duplexes that generally include the exon destined for editing and a cis-acting complementary sequence, usually found in a neighboring intron (2, 3). Because inosine is recognized by the translation machinery as guanosine (4), A-to-I editing in mRNAs can lead to the incorporation of amino acids differing from those specified by the literal genome.In Drosophila, the spectrum of ADAR substrates is peculiarly specific, consisting primarily of mRNAs encoding an array of voltage-and ligand-gated ion channels, as well as numerous pre-synaptic proteins involved in exo-and endocytosis of synaptic vesicles (5-8). Similarly, several mammalian ion channels and G-protein-coupled receptors are also subject to RNA editing (2, 7, 9 -11). In light of the ontological class and high sequence conservation of ADAR target genes, RNA editing has been invoked as an essential function in controlling synaptic transmission and neurophysiology. Correspondingly, deletion of the single Drosophila adar locus (dAdar) results in severe adult-stage behavioral abnormalities, including extreme uncoordination, seizures and a complete lack of courtship in dAdar null (dAdar 5g1 ) males (1...

show abstract

“…Secondly, recent studies have shown that epistatic interactions between editing sites in both the shaker potassium channel and the rdl GABA A receptor regulate protein function. 18,19 The fact that we were unable to fully recapitulate endogenous editing levels (leading to the generation of edited isoforms that may normally be very rare in vivo) suggests that the true adult-stage requirement for A-to-I editing is likely to be higher than our rescue data indicates, particularly when considering our transgenic RNAi data that shows a requirement for dADAR activity in nonneuronal tissues.…”

Section: Future Directionsmentioning

confidence: 95%

“…This conclusion is parsimonious with previous data showing that dAdar mRNA levels peak at later stages of development, 9 as does editing of many dADAR targets. [18][19][20] However, given the complexity of dADAR regulation, the diversity of target adenosines, and the potential for pleiotropic effects on development, gene regulation and neuronal firing properties in the absence of A-to-I editing, an absolutist position seems inappropriate. Although we failed to observe any negative epistasis between dAdar and a variety of RNAi components, interactions between these two pathways may still be physiologically relevant and open to natural selection.…”

Section: Future Directionsmentioning

confidence: 99%